Fluorescent entity, dyeing composition containing at least one fluorescent entity, and method for lightening keratin materials using said at least one fluorescent entity

ABSTRACT

The invention relates to a dye composition comprising a thiol/disulfide fluorescent dye comprising amino groups, and to a dyeing process which has a lightening effect on keratin materials, in particular keratin fibers, especially human keratin fibers such as the hair, using said composition. It similarly relates to novel thiol/disulfide fluorescent dyes and to uses thereof in lightening keratin materials. This composition makes it possible to obtain a particularly resistant and visible lightening effect on dark keratin fibers.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a national phase application based onPCT/FR2007/051003, filed Mar. 23, 2007, which claims the priority ofFrench Patent Application Nos. 0651035, filed Mar. 24, 2006, and0753070, filed Feb. 5, 2007; and claims the benefit of U.S. ProvisionalApplication Nos. 60/792,941, filed Apr. 19, 2006, and 60/900,361, filedFeb. 9, 2007, the contents of all of which are incorporated herein byreference.

The invention relates to the dyeing of keratin materials usingthiol/disulphide fluorescent dyes comprising one or more amino groups.

It is known practice to dye keratin fibres, in particular human keratinfibres, by direct dyeing. The process conventionally used in directdyeing comprises applying to the keratin fibres direct dyes which arecoloured or colouring molecules having an affinity for the fibres,allowing them to diffuse and then rinsing the fibres.

The direct dyes which are conventionally used are, for example, dyes ofthe nitrobenzene type, anthroquinone dyes, nitropyrridine dyes, or dyesof the azo, xanthene, acridine, azine or triarylmethane type.

The colourings which result from the use of direct dyes are temporary orsemipermanent colourings since the nature of the interactions which bindthe direct dyes to the keratin fibre and their disorption from thesurface and/or from the core of the fibre are responsible for their weakdyeing power and for their poor resistance to washing operations or toperspiration.

Moreover, the colouring of keratin fibres using conventional direct dyesdoes not make it possible to significantly lighten keratin fibres.

The lightening of the colour of keratin fibres, more particularly darkkeratin fibres to lighter shades, by optionally modifying the shadethereof, constitutes an important demand.

Conventionally, in order to obtain a lighter colouring, a chemicalbleaching process is used. This process comprises treating the keratinmaterials, such as keratin fibres, in particular the hair, with a strongoxidizing system, generally composed of hydrogen peroxide, possibly incombination with persalts, generally in an alkaline medium.

This bleaching system has the drawback of damaging keratin materials, inparticular keratin fibres, especially human keratin fibres such as thehair, and of detrimentally affecting their cosmetic properties. Thefibres in fact have a tendency to become rough, more difficult todisentangle and more brittle. Finally, the lightening or bleaching ofkeratin fibres using oxidizing agents is incompatible with thetreatments for modifying the shape of said fibres, particularly in hairstraightening treatments.

Another lightening technique comprises applying fluorescent direct dyesto dark hair. This technique, described in particular in documents FR 2830 189 and WO 2004/091473, makes it possible to retain the quality ofthe keratin fibre during the treatment, but the fluorescent dyes used donot exhibit satisfactory resistance to shampooing operations.

In order to increase the fastness of direct dyes, it is known practiceto fix direct dyes by covalent bonding to the hair. For example, it isknown practice to react dyes comprising reactive groups with the verynumerous cystine or cysteine residues in keratin fibres; see, forexample, Journal of the Society of Dyers and Colourists, Guise andStapleton, 91, 259-264 (1975); Journal of Cosmetic Chemistry, 42, 1-17(1991); CA 2024509.

Furthermore, it is known practice to protect the thiol function(s)contained in a molecule to be grafted to the hair before applying themto said hair, WO 99/51194.

Other disulphide dyes known for dyeing keratin fibres are disulphidederivatives of aminothiophenol derivatives. Such dyes are described, forexample, in patent FR 1156407. These dyes can be used under relativelymild conditions, in the presence of a slightly reducing medium or aftera reducing pretreatment of the hair. However, these dyes can bring aboutcolour changes during application.

Finally, document WO 2005/097051 describes azaimidazolium disulphidedyes for the direct dyeing of keratin fibres.

The aim of the present invention is to provide new systems for dyeingkeratin materials, in particular human keratin fibres, especially thehair, which do not have the drawbacks of the existing bleachingprocesses. In particular, one of the aims of the present invention is toprovide direct dyeing systems for obtaining lightening effects,especially on naturally or artificially dark keratin fibres, which areresistant to successive shampooing operations, which do not damage thekeratin fibres and which do not detrimentally affect their cosmeticproperties.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows the reflectance of the locks treated with pounds 1 and 2 atapplication and after 5 shampooing operations.

FIG. 2 shows the reflectance of the locks treated with compound 3 atapplication and after 5 shampooing operations.

FIG. 3 shows the reflectance of the locks treated with compound 5 atapplication and after 5 shampooing operations.

This aim is achieved with the present invention, a subject of which is aprocess for dyeing keratin materials, in particular keratin fibres,especially human keratin fibres such as the hair, more particularly darkhair, comprising applying, to the keratin materials, a dye compositioncomprising, in a cosmetically suitable medium, at least one thiolfluorescent dye, chosen from the dyes of formulae (I) and (II) below:

the organic or mineral acid salts, optical isomers and geometricalisomers thereof, and the solvates such as hydrates;

in which formulae (I) and (II):

-   -   R and R′″, which may be identical or different, represent a        hydroxyl group, an amino group (NR_(a)R_(b)) or an ammonium        group (N⁺R_(a)R_(b)R_(c)), An⁻; with R_(a), R_(b) and R_(c),        which may be identical or different, representing a hydrogen        atom or a (C₁-C₄) alkyl group; or else two alkyl groups R_(a)        and R_(b) of the amino or ammonium group form a heterocycle        comprising 5 to 7 members and optionally comprising another        heteroatom which may be identical to or different from that of        the nitrogen atom and An⁻ representing an anionic counterion;    -   R′ and R″, which may be identical or different, represent a        hydrogen atom or a group as defined for R and R′″ respectively;    -   R_(g), R′_(g), R″_(g), R′″_(g), R_(h), R′_(h), R″_(h) and        R′″_(h), which may be identical or different, represent a        hydrogen or halogen atom, an amino, (di)(C₁-C₄)alkylamino,        cyano, carboxyl, hydroxyl, trifluoromethyl, acylamino, C₁-C₄        alkoxy, C₂-C₄ (poly)hydroxyalkoxy, (C₁-C₄)alkylcarbonyloxy,        (C₁-C₄)alkoxycarbonyl, (C₁-C₄)alkylcarbonylamino, acylamino,        carbamoyl or (C₁-C₄)alkylsulphonylamino group, an aminosulphonyl        radical, or a (C₁-C₁₆)alkyl radical optionally substituted with        a group chosen from (C₁-C₁₂)alkoxy, hydroxyl, cyano, carboxyl,        amino and (di)(C₁-C₄)alkylamino, or else the two alkyl radicals        borne by the nitrogen atom of the amino group form a heterocycle        comprising 5 to 7 members and optionally comprising another        heteroatom which may be identical to or different from that of        the nitrogen atom;    -   R′_(i), R″_(i), R′″_(i) and R″″_(i), which may be identical or        different, represent a hydrogen atom or a (C₁-C₄)alkyl group;    -   m and m′, which may be identical or different, represent an        integer between 1 and 10 inclusive;    -   p, p′, q and q′, which may be identical or different, represent        an integer between 1 and 6 inclusive;    -   M′ represents an anionic counterion; and    -   Y represents: i) a hydrogen atom; ii) an alkali metal; iii) an        alkaline earth metal; iv) an ammonium group:        N⁺R^(α)R^(β)R^(γ)R^(δ) or a phosphonium group:        P⁺R^(α)R^(β)R^(γ)R^(δ) with R^(α), R^(β), R^(γ) and R^(δ), which        may be identical or different, representing a hydrogen atom or a        (C₁-C₄)alkyl group; or v) a thiol-function-protecting group;

it being understood that:

-   -   when the compound of formula (I) or (II) contains other cationic        parts, it is associated with one or more anionic counterions        allowing formula (I) or (II) to achieve electroneutrality.

Another subject of the invention is a dye composition comprising, in asuitable cosmetic medium, at least one fluorescent dye of formula (I) or(II) as defined above, and a reducing agent.

A subject of the invention is also novel fluorescent dyes of formula (I)or (II) as defined above.

The dyeing process according to the invention makes it possible tovisibly colour dark keratin materials, in particular dark human keratinfibres, especially dark hair.

Furthermore, the process of the invention makes it possible to obtaincolouring of keratin materials, in particular human keratin fibres,especially the hair, without damaging said material, which is persistentwith respect to shampooing operations, common attacks (sunlight,perspiration), and other hair treatments. The process of the inventionalso makes it possible to obtain lightening of keratin materials such askeratin fibres, in particular dark keratin fibres, and more particulardark hair.

For the purpose of the invention, the term “dark keratin material” isintended to mean that which exhibits a lightness of L* measured in theC.I.E.L. L*a*b* system of less than or equal to 45, and preferably lessthan or equal to 40, given that, moreover, L*=0 is equivalent to blackand L*=100 is equivalent to white.

For the purpose of the invention, the expression “naturally orartificially dark hair” is intended to mean hair whose tone height isless than or equal to 6 (dark blonde) and preferably less than or equalto 4 (chestnut-brown).

The lightening of the hair is evaluated by the variation in “toneheight” before or after application of the compound of formula (I) or(II).

The notion of “tone” is based on the classification of the naturalshades, one tone separating each shade from the shade immediatelyfollowing or preceding it. This definition and the classification of thenatural shades are well known to hair styling professionals and arepublished in the book “Science des traitement capillaires” [Hairtreatment sciences], by Charles Zviak 1988, published by Masson, pp. 215and 278.

The tone heights range from 1 (black) to 10 (very light blonde), oneunit corresponding to one tone; the higher the figure, the lighter theshade.

An artificially coloured hair is a hair whose colour has been modifiedby a dyeing treatment, for example dyeing with direct dyes or oxidationdyes.

Preferably, the composition should, after application to hair, forexample chestnut-brown hair, lead to the results below.

-   -   Interest is focused on the reflectance performance levels of the        hair when it is irradiated with visible light in the wavelength        range from 400 to 700 nanometres.    -   The curves of reflectance as a function of wavelength, of hair        treated with the composition of the invention and of untreated        hair, are then compared.    -   The curve corresponding to the treated hair should show a        reflectance in the wavelength range of from 500 to 700        nanometres which is higher than the curve corresponding to the        untreated hair.    -   This means that, in the wavelength range from 540 to 700        nanometres, there is at least one range where the reflectance        curve corresponding to the treated hair is higher than the        reflectance curve corresponding to the untreated hair. The term        “higher” is intended to mean a difference of at least 0.05% in        reflectance, preferably of at least 0.1%. All the same, there        may be, in the wavelength range of from 540 to 700 nanometres,        at least one range where the reflectance curve corresponding to        the treated hair is superimposable or lower than the reflectance        curve corresponding to the untreated hair.

Preferably, the wavelength where the difference is at a maximum betweenthe reflectance curve of the treated hair and that of the untreated hairis within the wavelength range of from 500 to 650 nanometres, andpreferably within the wavelength range of from 550 to 620 nanometres.

For the purpose of the present invention, and unless otherwiseindicated:

-   -   the “aryl” or “heteroaryl” radicals or the aryl or heteroaryl        part of a radical may be substituted with at least one        substituent borne by a carbon atom, chosen from:        -   a C₁-C₁₆ preferably C₁-C₈, alkyl radical optionally            substituted with one or more radicals chosen from the            radicals: hydroxyl, C₁-C₂ alkoxy, C₂-C₄(poly)hydroxyalkoxy,            acylamino and amino substituted with two C₁-C₄ alkyl            radicals, which may be identical or different, optionally            bearing at least one hydroxyl group, or the two radicals            possibly forming, with the nitrogen atom to which they are            attached, a heterocycle comprising from 5 to 7 members,            preferably 5 or 6 members, which is saturated or            unsaturated, which is optionally substituted, and which            optionally comprises another heteroatom which may be            identical or different from the nitrogen;        -   halogen atom such as chlorine, fluorine or bromine;        -   a hydroxyl group;        -   a C₁-C₂ alkoxy radical;        -   C₁-C₂ alkylthio radical;        -   a C₂-C₄ (poly)hydroxyalkoxy radical;        -   an amino radical;        -   a 5- or 6-membered heterocycloalkyl radical;        -   an optionally cationic 5- or 6-membered heteroaryl radical,            preferably imidazolium, optionally substituted with a C₁-C₄            alkyl radical, preferably methyl;        -   an amino radical substituted with one or two C₁-C₆ alkyl            radicals, which may be identical or different, optionally            bearing at least:            -   i) one hydroxyl group,            -   ii) one amino group optionally substituted with one or                two optionally substituted C₁-C₃ alkyl radicals, said                alkyl radicals possibly forming, with the nitrogen atom                to which they are attached, a heterocycle comprising                from 5 to 7 members, which is saturated or unsaturated,                which is optionally substituted, and which optionally                comprises at least one heteroatom which may or may not                be different from nitrogen,        -   —NR—COR′ in which the R radical is a hydrogen atom or a            C₁-C₄ alkyl radical optionally bearing at least one hydroxyl            group, and the R′ radical is a a C₁-C₂ alkyl radical;        -   (R)₂N—CO— in which the R radicals, which may or may not be            identical, represent a hydrogen atom, or a C₁-C₄ alkyl            radical optionally bearing at least one hydroxyl group;        -   R′SO₂—NR— in which the R radical represents a hydrogen atom            or a C₁-C₄ alkyl radical optionally bearing at least one            hydroxyl group, and the R′ radical represents a C₁-C₄ alkyl            radical or a phenyl radical;        -   (R)₂N—SO₂— in which the R radicals, which may or may not be            identical, represent a hydrogen atom or a C₁-C₄ alkyl            radical optionally bearing at least one hydroxyl group,        -   a carboxylic radical in acid or salified form (preferably            with an alkali metal or an ammonium, which is substituted or            unsubstituted);        -   a cyano group;        -   a polyhaloalkyl group containing from 1 to 6 carbon atoms            and from 1 to 6 halogen atoms, which may be identical or            different; the polyhaloalkyl group is, for example,            trifluoromethyl;    -   the cyclic or heterocyclic part of a nonaromatic radical may be        substituted with at least one substituent borne by a carbon        atom, chosen from the groups:        -   hydroxyl;        -   C₁-C₄ alkoxy;        -   C₂-C₄ (poly)hydroxyalkoxy;        -   a C₁-C₂ alkylthio radical;        -   RCO—NR′— in which the R′ radical is a hydrogen atom or a            C₁-C₄ alkyl radical optionally bearing at least one hydroxyl            group, and the R radical is a C₁-C₂ alkyl radical or an            amino radical substituted with two C₁-C₄ alkyl groups, which            may be identical or different, optionally bearing at least            one hydroxyl group;        -   RCO—O— in which the R radical is a C₁-C₄ alkyl radical or an            amino radical substituted with one or two C₁-C₄ alkyl            groups, which may be identical or different, optionally            bearing at least one hydroxyl group, said alkyl radicals            possibly forming, with the nitrogen atom to which they are            attached, a heterocycle comprising from 5 to 7 members,            which is saturated or unsaturated, which is optionally            substituted, and which optionally comprises at least one            other heteroatom which may or may not be different from            nitrogen;        -   RO—CO— in which the R radical is a C₁-C₄ alkyl radical            optionally bearing at least one hydroxyl group;    -   a cyclic or heterocyclic radical or a nonaromatic part of an        aryl or heteroaryl radical may also be substituted with one or        more oxo or thioxo groups;    -   an “aryl” radical represents a condensed or noncondensed,        monocyclic or polycyclic group containing from 6 to 22 carbon        atoms, and at least one ring of which is aromatic; preferably,        the aryl radical is a phenyl, biphenyl, naphthyl, indenyl,        anthracenyl or tetrahydronaphthyl;    -   a “diarylalkyl” radical represents a group comprising, on the        same carbon atom of an alkyl group, two aryl groups, which may        be identical or different, such as diphenylmethyl or        1,1-diphenylethyl;    -   a “heteroaryl radical” represents an optionally cationic,        condensed or noncondensed, monocyclic or polycyclic group        comprising from 5 to 22 members and from 1 to 6 heteroatoms        chosen from a nitrogen, oxygen, sulphur and selenium atom, and        at least one ring of which is aromatic; preferably, a heteroaryl        radical is chosen from acridinyl, benzimidazolyl,        benzobistriazolyl, benzopyrazolyl, benzopyridazinyl,        benzoquinolyl, benzothiazolyl, benzotriazolyl, benzoxazolyl,        pyridinyl, tetrazolyl, dihydrothiazolyl, imidazopyridinyl,        imidazolyl, indolyl, isoquinolyl, naphthoimidazolyl,        naphthooxazolyl, naphthopyrazolyl, oxadiazolyl, oxazolyl,        oxazolopyridyl, phenazinyl, phenooxazolyl, pyrazinyl, pyrazolyl,        pyrilyl, pyrazoyltriazyl, pyridyl, pyridinoimidazolyl, pyrrolyl,        quinolyl, tetrazolyl, thiadiazolyl, thiazolyl,        thiazolopyridinyl, thiazoylimidazolyl, thiopyrylyl, triazolyl,        xanthylyl and its ammonium salt;    -   a “diheteroarylalkyl” radical represents a group comprising, on        the same carbon atom of an alkyl group, two heteroaryl groups,        which may be identical or different, such as difurylmethyl,        1,1-difurylethyl, dipyrrolylmethyl or dithienylmethyl;    -   a “cyclic radical” is a condensed or noncondensed, monocyclic or        polycyclic, nonaromatic cycloalkyl radical containing from 5 to        22 carbon atoms, possibly comprising one or more unsaturations;        in particular, the cyclic radical is a cyclohexyl;    -   a “sterically hindered cyclic” radical is a substituted or        unsubstituted, aromatic or nonaromatic, cyclic radical hindered        by steric effect or constraint, comprising from 6 to 14 members,        which may be bridged; by way of sterically hindered radicals,        mention may be made of bicyclo[1.1.0]butane, mesityls such as        1,3,5-trimethylphenyl, 1,3,5-tri-tert-butylphenyl,        1,3,5-isobutylphenyl, 1,3,5-trimethylsilylphenyl and adamantyl;    -   a “heterocyclic radical or heterocycle” is a condensed or        noncondensed, monocyclic or polycyclic, nonaromatic radical        containing from 5 to 22 members, comprising from 1 to 6        heteroatoms chosen from nitrogen, oxygen, sulphur and selenium;    -   an “alkyl radical” is a linear or branched, C₁-C₁₆, preferably        C₁-C₈, hydrocarbon-based radical;    -   the expression “optionally substituted” assigned to the alkyl        radical implies that said alkyl radical may be substituted with        one or more radicals chosen from the radicals: i) hydroxyl; ii)        C₁-C₄ alkoxy; iii) acylamino; iv) amino optionally substituted        with one or two C₁-C₄ alkyl radicals, which may be identical or        different, said alkyl radicals possibly forming, with the        nitrogen atom which bears them, a heterocycle comprising from 5        to 7 members, optionally comprising another heteroatom which may        or may not be different from nitrogen; v) or a quaternary        ammonium group —N⁺R′R″R′″, M⁻ for which R′, R″, R′″, which may        be identical or different, represent a hydrogen atom or a C₁-C₄        alkyl group, or else —N⁺R′R″R′″ forms a heteroaryl such as        imidazolium optionally substituted with a C₁-C₄ alkyl group, and        M⁻ represents the counterion of the corresponding organic acid,        mineral acid or halide;    -   an “alkoxy radical” is an alkyloxy or alkyl-O-radical for which        the alkyl radical is a linear or branched, C₁-C₁₆, preferably        C₁-C₈, hydrocarbon-based radical;    -   an “alkylthio radical” is an alkyl-S— radical for which the        alkyl radical is a linear or branched, C₁-C₁₆, preferably C₁-C₈,        hydrocarbon-based radical; when the alkylthio group is        optionally substituted, this implies that the alkyl group is        optionally substituted as defined above;    -   the limits delimiting the extent of the range of values are        included in this range of values;    -   an “organic or mineral acid salt” is more particularly chosen        from a salt derived: i) from hydrochloric acid HCl; ii) from        hydrobromic acid HBr; iii) from sulphuric acid H₂SO₄; iv) from        alkylsulphonic acids: Alk-S(O)₂OH such as methylsulphonic acid        and ethylsulphonic acid; v) from arylsulphonic acids: Ar—S(O)₂OH        such as from benzenesulphonic acid and from toluenesulphonic        acid; vi) from citric acid; vii) from succinic acid; viii) from        tartaric acid; ix) from lactic acid; x) from alkoxysulphinic        acids: Alk-O—S(O)OH such as from methoxysulphinic acid and from        ethoxysulphinic acid; xi) from aryloxysulphinic acids such as        from tolueneoxysulphinic acid and from phenoxysulphinic        acid; xii) from phosphoric acid H₃PO₄; xiii) from acetic acid        CH₃COOH; xiv) from triflic acid CF₃SO₃H and xv) from        tetrafluoroboric acid HBF₄;    -   an “anionic counterion” is an anion or an anionic group        associated with the cationic charge of the dye; more        particularly, the anionic counterion is chosen from: i) halides        such as chloride or bromide; ii) nitrates; iii) sulphonates,        among which are C₁-C₆ alkyl sulphonates: Alk-S(O)₂O⁻ such as        methyl sulphonate or mesylate and ethyl sulphonate; iv) aryl        sulphonates: Ar—S(O)₂O⁻ such as benzene sulphonate and        toluenesulphonate or tosylate; v) citrate; vi) succinate; vii)        tartrate; viii) lactate; ix) alkyl sulphates: Alk-O—S(O)O⁻ such        as methyl sulphate and ethyl sulphate; x) arylsulphates:        Ar—O—S(O)O⁻ such as benzenesulphate and toluenesulphate; xi)        alkoxysulphates: Alk-O—S(O)₂O⁻ such as methoxy sulphate and        ethoxy sulphate; xii) aryloxysulphates: Ar—O—S(O)₂O⁻; xiii)        phosphate; xiv) acetate; xv) triflate; and xvi) borates such as        tetrafluoroborate.

The fluorescent dyes of formula (I) or (II) are compounds capable ofabsorbing in the UV radiation or visible range at a wavelength λ_(abs)of between 250 and 800 nm and capable of re-emitting in the visiblerange at an emission wavelength λ_(em) of between 400 and 800 nm.

Preferably, the thiol fluorescent compounds of the invention are dyescapable of absorbing in the visible range λ_(abs) of between 400 and 800nm and of re-emitting in the visible range λ_(em) of between 400 and 800nm. More preferably, the fluorescent dyes of formula (I) or (II) aredyes capable of absorbing at a λ_(abs) of between 420 nm and 550 nm andof re-emitting in the visible range at a λ_(em) of between 470 and 600nm.

The fluorescent compounds of formula (II) of the invention contain an SYfunction which may be in the covalent form —S—Y or ionic form —S⁻Y⁺depending on the nature of Y and on the pH of the medium.

A specific embodiment relates to the thiol fluorescent dyes comprising agroup of formula (II) comprising an SY function where Y represents ahydrogen atom or an alkali metal. Advantageously, Y represents ahydrogen atom.

In accordance with another specific embodiment of the invention, in theabovementioned formula (II), Y is a protecting group known to thoseskilled in the art, for instance those described in the books“Protective Groups in Organic Synthesis”, T. W. Greene, John Willey &Sons publisher, NY, 1981, pp. 193-217; “Protecting Groups”, P.Kocienski, Thieme, 3rd ed., 2005, chap. 5.

Particularly when Y represents a thiol-function-protecting group, Y ischosen from the following radicals:

-   -   (C₁-C₄)alkylcarbonyl;    -   (C₁-C₄)alkylthiocarbonyl;    -   (C₁-C₄)alkoxycarbonyl;    -   (C₁-C₄)alkoxythiocarbonyl;    -   (C₁-C₄)alkylthiothiocarbonyl;    -   (di)(C₁-C₄)(alkyl)aminocarbonyl;    -   (di)(C₁-C₄)(alkyl)aminothiocarbonyl;    -   arylcarbonyl such as phenylcarbonyl;    -   aryloxycarbonyl;    -   aryl(C₁-C₄)alkoxycarbonyl;    -   (di)(C₁-C₄)(alkyl)aminocarbonyl such as dimethylaminocarbonyl;    -   (C₁-C₄)(alkyl)arylaminocarbonyl;    -   carboxyl;    -   SO₃ ⁻, M⁺ with M⁺ representing an alkali metal such as sodium or        potassium, or else M′ of formula (II) and M⁺ are absent;    -   optionally substituted aryl such as phenyl, dibenzosuberyl or        1,3,5-cycloheptatrienyl,    -   optionally substituted heteroaryl; including in particular the        cationic or noncationic heteroaryl comprising from 1 to 4        heteroatoms below:        -   i) monocyclic comprising 5, 6 or 7 members, such as furanyl            or furyl, pyrrolyl or pyrryl, thiophenyl or thienyl,            pyrazolyl, oxazolyl, oxazolium, isoxazolyl, isoxazolium,            thiazolyl, thiazolium, isothiazolyl, isothiazolium,            1,2,4-triazolyl, 1,2,4-triazolium, 1,2,3-triazolyl,            1,2,3-triazolium, 1,2,4-oxazolyl, 1,2,4-oxazolium,            1,2,4-thiadiazolyl, 1,2,4-thiadiazolium, pyrylium,            thiopyridyl, pyridinium, pyrimidinyl, pyrimidinium,            pyrazinyl, pyrazinium, pyridazinyl, pyridazinium, triazinyl,            triazinium, tetrazinyl, tetrazinium, azepine, azepinium,            oxazepinyl, oxazepinium, thiepinyl, thiepinium, imidazolyl,            imidazolium;        -   ii) bicyclic comprising 8 to 11 members, such as indolyl,            indolinium, benzoimidazolyl, benzoimidazolium, benzoxazolyl,            benzoxazolium, dihydrobenzoxazolinyl, benzothiazolyl,            benzothiazolium, pyridoimidazolyl, pyridoimidazolium,            thienocycloheptadienyl, these monocyclic or bicyclic groups            being optionally substituted with one or more groups such as            (C₁-C₄)alkyl, for instance methyl, or polyhalo(C₁-C₄)alkyl,            for instance trifluoromethyl;        -   iii) or tricyclic ABC below:

-   -   -   -   in which the two rings A, C optionally comprise a                heteroatom, and the ring B is a 5-, 6- or 7-membered,                particularly 6-membered ring and contains at least one                heteroatom, for instance piperidyl or pyranyl;

    -   optionally cationic, optionally substituted heterocycloalkyl,        the heterocycloalkyl group represents in particular a saturated        or partially saturated, 5-, 6- or 7-membered monocyclic group        comprising from 1 to 4 heteroatoms chosen from oxygen, sulphur        and nitrogen, such as di/tetrahydrofuranyl,        di/tetrahydrothiophenyl, di/tetrahydropyrrolyl,        di/tetrahydropyranyl, di/tetra/hexahydrothiopyranyl,        dihydropyridyl, piperazinyl, piperidinyl,        tetramethylpiperidinyl, morpholinyl, di/tetra/hexahydroazepinyl        or di/tetrahydropyrimidinyl, these groups being optionally        substituted with one or more groups such as (C₁-C₄) alkyl, oxo        or thioxo; or the heterocycle represents the following group:

-   -   -   in which R′^(c), R′^(d), R′^(e), R′^(f), R′^(g) and R′^(h),            which may be identical or different, represent a hydrogen            atom or a (C₁-C₄) alkyl group, or else two groups R′^(g)            with R′^(h), and/or R′^(e) with R′^(f), form an oxo or            thioxo group, or else R′^(g) with R′^(e) together form a            cycloalkyl; and v represents an integer between 1 and 3            inclusive; preferably, R′^(c) to R′^(h) represent a hydrogen            atom; and An⁻ represents a counterion;

    -   isothiouronium —C(NR′^(c)R′^(d))═N⁺R′^(e)R′^(f); An⁻ with        R′^(c), R′^(d), R′^(e) and R′^(f), which may be identical or        different, represent a hydrogen atom or a (C₁-C₄)alkyl group;        preferably, R′^(c) to R′^(f) represent a hydrogen atom; and An⁻        represents a counterion;

    -   isothiourea —C(NR′^(c)R′^(d))═NR′^(e); with R′^(c), R′^(d), and        R′^(e) as defined above;

    -   optionally substituted (di)aryl(C₁-C₄)alkyl, such as        9-anthracenylmethyl, phenylmethyl or diphenylmethyl optionally        substituted with one or more groups in particular chosen from        (C₁-C₄) alkyl, (C₁-C₄) alkoxy such as methoxy, hydroxyl,        (C₁-C₄)alkylcarbonyl and (di)(C₁-C₄)(alkyl)amino such as        dimethylamino;

    -   optionally substituted (di)heteroaryl(C₁-C₄)alkyl, the        heteroaryl group is in particular cationic or noncationic, and        monocyclic, comprising 5 or 6 members and from 1 to 4        heteroatoms chosen from nitrogen, oxygen and sulphur, such as        the groups pyrrolyl, furanyl, thiophenyl, pyridyl, pyridyl        N-oxide such as 4-pyridyl or 2-pyridyl N-oxide, pyrylium,        pyridinium or triazinyl, optionally substituted with one or more        groups such as alkyl, particularly methyl, advantageously the        (di)heteroaryl(C₁-C₄)alkyl is (di)heteroarylmethyl or        (di)heteroarylethyl;

    -   CR¹R²R³ with R¹, R² and R³, which may be identical or different,        representing a halogen atom or a group chosen from:        -   (C₁-C₄) alkyl;        -   (C₁-C₄) alkoxy;        -   optionally substituted aryl, such as phenyl optionally            substituted with one or more groups such as (C₁-C₄)alkyl,            (C₁-C₄)alkoxy or hydroxyl;        -   optionally substituted heteroaryl, such as thiophenyl,            furanyl, pyrrolyl, pyranyl or pyridyl, optionally            substituted with a (C₁-C₄)alkyl group;        -   P (Z¹)R′¹R′²R′³ with R′¹ and R′², which may be identical or            different, representing a hydroxyl, (C₁-C₄)alkoxy or alkyl            group, R′³ representing a hydroxyl or (C₁-C₄)alkoxy group            and Z¹ representing an oxygen or sulphur atom;

    -   a sterically hindered cyclic group such as the adamantyl group;        and

    -   optionally substituted alkoxy(C₁-C₄)alkyl, such as methoxymethyl        (MOM), ethoxyethyl (EOM) or isobutoxymethyl.

According to a specific embodiment, the protected thiol fluorescent dyesof formula (II) comprising a group Y i) which is a cationic, aromatic 5-or 6-membered monocyclic heteroaryl group comprising from 1 to 4heteroatoms chosen from oxygen, sulphur and nitrogen, such as oxazolium,isoxazolium, thiazolium, isothiazolium, 1,2,4-triazolium,1,2,3-triazolium, 1,2,4-oxazolium, 1,2,4-thiadiazolium, pyrylium,pyridinium, pyrimidinium, pyrazinyl, pyrazinium, pyridazinium,triazinium, tetrazinium, oxazepinium, thiepinyl, thiepinium orimidazolium; ii) cationic 8- to 11-membered bicyclic heteroaryl group,such as indolinium, benzoimidazolium, benzoxazolium or benzothiazolium,these monocyclic or bicyclic heteroaryl groups being optionallysubstituted with one or more groups such as alkyl, for instance methyl,or polyhalo(C₁-C₄)alkyl, for instance trifluoromethyl; iii) orheterocyclic group below:

in which R′^(c) and R′^(d), which may be identical or different,represent a hydrogen atom or a (C₁-C₄)alkyl group; preferably, R′^(c) toR′^(d) represent a (C₁-C₄)alkyl group such as methyl; and An⁻ representsa counterion.

In particular, Y represents a group chosen from oxazolium, isoxazolium,thiazolium, isothiazolium, 1,2,4-triazolium, 1,2,3-triazolium,1,2,4-oxazolium, 1,2,4-thiadiazolium, pyrylium, pyridinium,pyrimidinium, pyrazinium, pyridazinium, triazinium, imidazolium,benzoimidazolium, benzoxazolium and benzothiazolium, these groups beingoptionally substituted with one or more (C₁-C₄) alkyl groups, inparticular methyl.

In particular, Y represents an alkali metal or a protecting group suchas:

-   -   (C₁-C₄)alkylcarbonyl, such as methylcarbonyl or ethylcarbonyl;    -   arylcarbonyl such as phenylcarbonyl;    -   (C₁-C₄)alkoxycarbonyl;    -   aryloxycarbonyl;    -   aryl(C₁-C₄)alkoxycarbonyl;    -   (di)(C₁-C₄)(alkyl)aminocarbonyl such as dimethylaminocarbonyl;    -   (C₁-C₄)(alkyl)arylaminocarbonyl;    -   optionally substituted aryl, such as phenyl;    -   5- or 6-membered monocyclic heteroaryl, such as imidazolyl or        pyridyl;    -   5- or 6-membered cationic monocyclic heteroaryl, such as        pyrylium, pyridinium, pyrimidinium, pyrazinium, pyridazinium,        triazinium or imidazolium; these groups being optionally        substituted with one or more identical or different (C₁-C₄)alkyl        groups, such as methyl;    -   8- to 11-membered cationic bicyclic heteroaryl, such as        benzoimidazolium or benzoxazolium; these groups being optionally        substituted with one or more identical or different (C₁-C₄)alkyl        groups, such as methyl;    -   cationic heterocycle of formula below:

-   -   isothiouronium —C(NH₂)═N⁺H₂; An⁻;    -   isothiourea —C(NH₂)═NH; or    -   SO₃ ⁻, M⁺ with M⁺ representing an alkali metal such as sodium or        potassium, or else M′ of formula (II) and M′ are absent.

According to a specific embodiment of the invention, the dyes of theinvention belong to formula (Ia) or (IIa) which have an ethylene grouplinking the pyridinium part to the phenyl at the ortho- or para-positionwith respect to the pyridinium, i.e. at 2-4′, 4-2′, 4-4′:

with R, R′, R″, R′″, R_(g), R′_(g), R″_(g), R′″_(g), R_(h), R′_(h),R″_(h), R′″_(h), R′_(i), R″_(i), R′″_(i), R″″_(i), m, m′, p, p′, q, q′,Y and M′ being as defined above. In particular, R_(h) and R″_(h) are inthe ortho-position with respect to the pyridinium group and R′_(h) andR″_(h) represent a hydrogen atom. Another aspect of the inventionconcerns the dyes of formula (Ia) or (IIa) having R_(g) and R″_(g)groups in the 3′-position and R′_(g)/R″_(g) which represent a hydrogenatom.

Advantageously, the dyes of formulae (Ia) and (IIa) have their aminogroup: R′(CH₂)_(p′)—N—(CH₂)_(q′)—R and/or R″(CH₂)_(p′)—N—(CH₂)_(q′)—R′″in the 1′-position.

By way of example of thiol fluorescent dyes, mention may in particularbe made of the following compounds:

with M′ representing an anionic counterion.

The protected thiol dyes of formula (II′) can be synthesized in twostages. The first stage consists in preparing the nonprotected thiol dye(II-H) according to the methods known to those skilled in the art, forinstance “Thiols and organic Sulfides”, “Thiocyanates andIsothiocyanates, organic”, Ullmann's Encyclopaedia, Wiley-VCH, Weinheim,2005. In addition, the second stage consists in protecting the thiolfunction according to the conventional methods known to those skilled inthe art for producing protected thiol dyes of formula (II′). By way ofexample for protecting the thiol function —SH of the thiol dye, use maybe made of the methods in the books “Protective Groups in OrganicSynthesis”, T. W. Greene, John Willey & Sons ed., NY, 1981, pp. 193-217;“Protecting Groups”, P. Kocienski, Thieme, 3rd ed., 2005, chap. 5.

This method can be illustrated by means of the method consisting i) ingenerating thiol fluorescent dyes of formula (II-H) by reduction of atwo-chromophore fluorescent dye bearing a disulphide function —S—S-(I′)and ii) in protecting, according to the conventional methods, said thiolfunction of (II-H) with the reactant 7 Y′R in order to obtain theprotected thiol fluorescent dyes of formula (II′). The thiol compound 6can also be metallated with an alkali metal or alkaline earth metal Met*so as to produce the thiolate fluorescent dye of formula (II″).

with Y′ representing a thiol-function-protecting group; Met*representing an alkali metal or an alkaline earth metal, particularlysodium or potassium, it being understood that, when the metal is analkaline earth metal, 2 chromophores comprising a thiolate function S⁻can be associated with one metal²⁺;

and with R, R′, R_(g), R′_(g), R_(h), R′_(h), R′_(i), R″_(i), m, p, qand M′ being as defined above; Y′ represents a thiol-function-protectinggroup; and R of Y′R represents a nucleofuge leaving group, for instancemesylate, tosylate, triflate or halide.

Use may also be made of a thiol reactant Y′—SH comprising a Y′ group asdefined above, the nucleophilic SH function of which can react with thecarbon atom in the alpha-position with respect to the halogen atom borneby the fluorescent chromophore (a′) so as to give the protected thiolfluorescent dye of formula (II′):

with R, R′, R_(g), R′_(g), R_(h), R′_(h), R′_(i), R″_(i), m, p, q andM′, (II′) being as defined above, and Hal representing a nucleofugehalogen atom such as bromine, iodine or chlorine.

More particularly, a nucleofuge leaving group may be substituted with athiourea group (S═C(NRR)NRR) so as to generate the isothiouroniums. Forexample, if the thiourea group is a thioimidazolinium (β), the reactionscheme is the following:

with R, R′, R_(g), R′_(g), R_(h), R′_(h), R′_(i), R″_(i), m, p, q and M′being as defined above.

A variant is to use, in place of the halide comprising the fluorescentchromophore (a′), a chromophore comprising another type of nucleofugesuch as tosylate or mesylate.

By way of example, a compound containing a protected thiol groupcontains a nucleofuge leaving group R, for instance mesylate, tosylateor triflate, which can undergo nucleophilic attack from the amine borneby the styryl fluorescent chromophore:

Another alternative comes from the use of halides as nucleofuge leavinggroup on a thiol compound that may be substituted with a primary aminefunction, for example, borne by a styryl fluorescent chromophore:

In accordance with another possibility, the thiol fluorescent dyes offormula (II) according to the invention may be obtained by reaction of acompound comprising a thiol group Y as defined above and anelectrophilic group (f) with a pyridinium compound comprising anucleophilic group. By way of example, an aldehyde, ketone orthioaldehyde, or a thioketone when G′ represents an oxygen or sulphuratom, may be condensed with an “activated methylene” such asalkylpyridinium (e) so as to generate a >C═C< ethylene bond. Thisreaction is commonly known as “Knoevenagel” condensation. The term“activated methylenes” is intended to mean those which preferentiallycomprise, in the 2- or 4-position with respect to the pyridinium group,a methylene group R_(i)—CH₂—:

with R, R′, R_(g), R′_(g), R_(h), R′_(h), R′_(i), R″_(i), m, p, q, Y andM′ as defined above and G′ representing an oxygen or sulphur atom.

Reference may be made to the book Advanced Organic Chemistry,“Reactions, Mechanisms and Structures”, J. March, 4th ed. John Willey &Sons, 1992 or T. W. Greene “Protective Groups in Organic Synthesis”, forfurther details on the operating conditions used for the processesmentioned above.

The thiol fluorescent dyes formed may be converted to —S Y′ protectedthiol fluorescent dyes by protection of the —SH thiol using conventionalprotecting groups. The thiol fluorescent dyes are metallated by alsousing the conventional methods known to those skilled in the art, suchas those described in Advanced Organic Chemistry, “Reactions, Mechanismsand Structures”, J. March, 4th ed. John Willey & Sons, NY, 1992.

The protected thiol dyes can be deprotected by conventional routes suchas those described in the books “Protective Groups in OrganicSynthesis”, T. W. Greene, John Willey & Sons ed., NY, 1981; “ProtectingGroups”, P. Kocienski, Thieme, 3rd ed., 2005.

The starting reactants are commercially available or accessible byconventional methods known to those skilled in the art. By way ofexample, it is possible to synthesize the symmetrical thiol fluorescentdye (I′) using 2 equivalents of pyridine derivative 1 and one equivalentof disulphide reactant comprising two leaving groups Gp, so as to givethe dipyridinium disulphide salt 3 which can in turn be condensed withtwo equivalents of aryl compound comprising an aldehyde/thioaldehydegroup, 4, to give (I′).

with Lg representing a nucleofuge leaving group, for instance mesylate,tosylate, triflate or halide. The Lg⁻ counterions of the compounds (I′),above, can be replaced with M′ counterions of other natures, usingmethods known to those skilled in the art, in particular by ion exchangeresin.

The disymmetrical disulphide dyes of formula (I) can be synthesized in asingle stage by reacting a nonprotected thiol fluorescent dye with athiol fluorescent dye protected by Y′, so as to form the disulphide dyeof formula (I)

with R, R′, R″, R′″, R_(g), R′_(g), R″_(g), R′″_(g), R_(h), R′_(h),R″_(h), R′″_(h), R_(i), R′_(i), R″_(i), R′″_(i), m, m′, p, p′, q, q′ andM′ as defined above; Y′ represents a thiol-function-protecting group.

Reference may be made to the book Advanced Organic Chemistry,“Reactions, Mechanisms and Structures”, J. March, 4th ed. John Willey &Sons, 1992 or T. W. Greene “Protective Groups in Organic Synthesis”, forfurther details on the operating conditions used for the processesmentioned above.

The thiol fluorescent dyes formed can be converted to —S Y′ protectedthiol fluorescent dyes by protection of the —SH thiol using conventionalprotecting groups. The thiol fluorescent dyes are metallated by alsousing the conventional methods known to those skilled in the art, suchas those described in Advanced Organic Chemistry, “Reactions, Mechanismsand Structures”, J. March, 4th ed. John Willey & Sons, NY, 1992.

The protected thiol dyes can be deprotected by conventional routes suchas those described in the books “Protective Groups in OrganicSynthesis”, T. W. Greene, John Willey & Sons ed., NY, 1981; “ProtectingGroups”, P. Kocienski, Thieme, 3rd ed., 2005.

The composition of the invention contains at least one fluorescent dyeof formula (I) or (II). In addition to the presence of at least onefluorescent dye of formula (I) or (II), the composition of the inventionmay also contain a reducing agent.

This reducing agent may be chosen from thiols, for example cysteine,homocysteine or thiolactic acid, the salts of these thiols, thephosphines, the bisulphite, the sulphites, thioglycolic acid, and alsoits esters, in particular glycerol monothioglycolate, and thioglycerol.This reducing agent may also be chosen from borohydrides and derivativesthereof, for instance the salts of borohydride, of cyanoborohydride, ortriacetoxyborohydride or of trimethoxyborohydride: sodium salts, lithiumsalts, potassium salts, calcium salts, quaternary ammonium(tetramethylammonium, tetraethylammonium, tetra-n-butylammonium orbenzyltriethylammonium) salts; catechol borane.

The dye composition that can be used in the invention generally containsan amount of fluorescent dye of formula (I) or (II) of between 0.001%and 50% relative to the total weight of the composition. Preferably,this amount is between 0.005% and 20% by weight, and even morepreferably between 0.01% and 5% by weight, relative to the total weightof the composition.

The dye composition may also contain additional direct dyes. Thesedirect dyes are, for example, chosen from neutral, acidic or cationicnitrobenzene direct dyes, neutral, acidic or cationic azo direct dyes,tetraazapentamethine dyes, neutral, acidic or cationic quinone, inparticular anthraquinone dyes, azine direct dyes, triarylmethane directdyes, indoamine direct dyes and natural direct dyes.

Among the natural direct dyes, mention may be made of lawsone, juglone,alizarin, purpurin, carminic acid, kermesic acid, purpurogallin,protocatechaldehyde, indigo, isatin, curcumin, spinulosin andapigenindin. Extracts or decoctions containing these natural dyes, andin particular poultices or henna-based extracts, may also be used.

The dye composition may contain one or more oxidation bases and/or oneor more couplers conventionally used for dyeing keratin fibres.

Among the oxidation bases, mention may be made ofpara-phenylenediamines, bisphenylalkylenediamines, para-aminophenols,bis-para-aminophenols, ortho-aminophenols, heterocyclic bases, andaddition salts thereof.

Among these couplers, mention may in particular be made ofmeta-phenylenediamines, meta-aminophenols, meta-diphenols, naphthalenecouplers, heterocyclic couplers, and addition salts thereof.

The coupler(s) is (are) each generally present in an amount of between0.001% and 10% by weight of the total weight of the dye composition,preferably between 0.005% and 6%.

The oxidation base(s) present in the dye composition is (are) in generaleach present in an amount of between 0.001% and 10% by weight of thetotal weight of the dye composition, preferably between 0.005% and 6% byweight.

In general, the addition salts of the oxidation bases and of thecouplers that can be used in the context of the invention are inparticular chosen from addition salts with an acid, such ashydrochlorides, hydrobromides, sulphates, citrates, succinates,tartrates, lactates, tosylates, benzenesulphonates, phosphates andacetates, and addition salts with a base, such as hydroxides of analkali metal such as sodium or potassium, aqueous ammonia, amines oralkanolamines.

The medium suitable for dyeing, also called dye support, is a cosmeticmedium generally constituted of water or of a mixture of water and atleast one organic solvent. By way of organic solvent, mention may, forexample, be made of C₁-C₄ lower alkanols, such as ethanol andisopropanol; polyols and polyol ethers, such as 2-butoxyethanol,propylene glycol, propylene glycol monomethyl ether, diethylene glycolmonoethyl ether and diethylene glycol monomethyl ether, and alsoaromatic alcohols such as benzyl alcohol or phenoxyethanol, and mixturesthereof.

The solvents, when they are present, are preferably present inproportions of preferably between 1% and 40% by weight approximately,relative to the total weight of the dye composition, and even morepreferably between 5% and 30% by weight approximately.

According to one variant, the invention contains a reducing agentcapable of reducing the disulphide bonds of keratin and/or of the dye offormula (I). This reducing agent is as defined above.

The dye composition may also contain various adjuvants conventionallyused in hair-dyeing compositions, such as anionic, cationic, nonionic,amphoteric or zwitterionic surfactants or mixtures thereof, anionic,cationic, nonionic, amphoteric or zwitterionic polymers, or blendsthereof, mineral or organic thickeners, and in particular anionic,cationic, nonionic and amphoteric associative polymer thickeners,antioxidants, penetrating agents, sequestering agents, fragrances,buffers, dispersing agents, conditioning agents such as, for example,modified or unmodified, volatile or non-volatile silicones, such asamino film-forming agents, ceramides, preservatives, opacifiers orconductive polymers.

The above adjuvants are in general present in an amount, for each ofthem, of between 0.01% and 20% by weight relative to the weight of thecomposition.

Of course, those skilled in the art will take care to select this orthese possible additional compounds in such a way that the advantageousproperties intrinsically associated with the dye composition inaccordance with the invention are not, or are not substantially,impaired by the addition(s) envisaged.

The pH of the dye composition is generally between 4 and 14approximately, and preferably between 5 and 11 approximately. It may beadjusted to the desired value by means of acidifying or basifying agentsnormally used in the dyeing of keratin fibres or else by means ofconventional buffer systems.

Among the acidifying agents, mention may, by way of example, be made ofmineral or organic acids, such as hydrochloric acid, orthophosphoricacid, sulphuric acid, carboxylic acids, for instance acetic acid,tartaric acid, citric acid or lactic acid, or sulphonic acids.

Among the basifying agents, mention may, by way of example, be made ofaqueous ammonia, alkali carbonates, alkanolamines such as mono-, di- andtriethanolamines, and also derivatives thereof, sodium hydroxide orpotassium hydroxide and the compounds of formula (γ) below:

in which W_(a) is a propylene residue optionally substituted with ahydroxyl group or a C₁-C₄ alkyl radical; R_(a1), R_(a2), R_(a3) andR_(a4), which may be identical or different, represent a hydrogen atom,a C₁-C₄ alkyl radical or a C₁-C₄ hydroxyalkyl radical.

The dye composition may be in various forms, such as in the form of aliquid, a cream or a gel, or in any other form suitable for dyeingkeratin fibres, and in particular the hair.

According to a specific embodiment in the process of the invention, areducing agent may be applied as a pretreatment before the applicationof the composition containing at least one fluorescent dye of formula(I) or (II).

This reducing agent may be chosen from thiols, for example cysteine,homocysteine or thiolactic acid, the salts of these thiols, thephosphines, the bisulphite, the sulphites, thioglycolic acid, and alsoits esters, in particular glyceryl monothioglycolate, and thioglycerol.This reducing agent may also be chosen from borohydrides and derivativesthereof, for instance the salts of borohydride, of cyanoborohydride, oftriacetoxyborohydride or of trimethoxyborohydride: sodium salts, lithiumsalts, potassium salts, calcium salts, quaternary ammonium(tetramethylammonium, tetraethylammonium, tetra-n-butylammonium,benzyltriethylammonium) salts; catechol borane.

This pretreatment may be of short duration, in particular from 0.1second to 30 minutes, preferably from 1 minute to 15 minutes, with areducing agent as mentioned above.

According to another process, the composition comprising at least onefluorescent dye of formula (I) or (II) also contains at least onereducing agent as defined above. This composition is then applied to thehair.

When the thiol fluorescent dye of formula (II) comprises athiol-function-protecting group Y, the process of the invention may bepreceded by a deprotection step aimed at restoring the SH function insitu.

By way of example, it is possible to deprotect the S—Y function with a Yprotecting group by adjusting the pH as follows:

Y: Protecting group Deprotection alkylcarbonyl pH > 9 arylcarbonyl pH >9 alkoxycarbonyl pH > 9 aryloxycarbonyl pH > 9 arylalkoxycarbonyl pH > 9(di)(alkyl)aminocarbonyl pH > 9 (alkyl)arylaminocarbonyl pH > 9optionally substituted aryl, such as phenyl pH > 9 5-,6- or 7-memberedmonocyclic heteroaryl pH > 9 such as oxazolium 8- to 11-memberedbicyclic heteroaryl, such pH > 9 as benzoimidazolium or benzoxazolium

The deprotection step can also be carried out during a hair pretreatmentstep, for instance reducing pretreatment of the hair.

According to one variant, the reducing agent is added to the dyecomposition containing at least one fluorescent dye of formula (I) or(II) at the time of use.

According to another process, the composition comprising at least onefluorescent dye of formula (I) or (II) also contains at least onereducing agent as defined above. This composition is then applied to thehair.

According to another variant, the reducing agent is applied as apost-treatment, after the application of the composition containing atleast one fluorescent dye of formula (I) or (II). The duration of thepost-treatment with the reducing agent may be short, for example from0.1 second to 30 minutes, preferably from 1 minute to 15 minutes, with areducing agent as described above. According to a specific embodiment,the reducing agent is an agent of thiol or borohydride type as describedabove.

A specific embodiment of the invention relates to a process in which thefluorescent dye of formula (I) or (II) can be applied directly to thehair without reducing agents, free of reducing pretreatment or reducingpost-treatment.

A treatment with an oxidizing agent may optionally be combined. Any typeof oxidant conventional in the field may be used. Thus, it may be chosenfrom hydrogen peroxide, urea peroxide, alkali metal bromates, persaltssuch as perborates and persulphates, and also enzymes, among whichmention may be made of peroxidases, 2-electron oxidoreductases such asuricases and 4-electron oxygenases such as laccases. The use of hydrogenperoxide is particularly preferred.

This oxidizing agent can be applied to the fibres before or after theapplication of the composition containing at least one fluorescent dyeof formula (I) or (II).

The application of the dye composition according to the invention isgenerally carried out at ambient temperature. It may, however, becarried out at temperatures ranging from 20 to 180° C.

A subject of the invention is also a multicompartment device or dyeingkit in which a first compartment contains a dye composition comprisingat least one fluorescent dye of formula (I) or (II) and a secondcompartment contains a reducing agent capable of reducing the disulphidefunctions of keratin materials.

One of these compartments may also contain one or more other dyes ofdirect dye or oxidation dye type.

The invention also relates to a multicompartment device in which a firstcompartment contains a dye composition comprising at least onefluorescent dye of formula (I) or (II); a second compartment contains areducing agent capable of reducing the disulphide bond of keratinmaterials; and a third compartment contains an oxidizing agent.

Alternatively, the dyeing device contains a first compartment containinga dye composition which comprises at least one protected thiolfluorescent dye of formula (II) and a second compartment containing anagent capable of deprotecting the protected thiol so as to free thethiol.

Each of the devices mentioned above may be equipped with a means fordelivering the desired mixture to the hair, for example such as thedevices described in patent FR 2 586 913.

The examples which follow serve to illustrate the invention without,however, being limiting in nature. The thiol fluorescent dyes of theexamples hereinafter have been entirely characterized by conventionalspectroscopic and spectrometric methods.

EXAMPLES Synthesis Examples Example 1 Synthesis of1,1′-(disulphanediyldiethane-2,1-diyl)bis[4-((E)-2-{4-[bis(2-hydroxyethyl)amino]-phenyl}vinyl)pyridinium]dimethanesulphonate [1]

Procedure

Stage 1 Synthesis of disulphanediyldiethane-2,1-diyl dimethanesulphonate

10 g of 2,2′-dithiodiethanol and 14.44 g of triethylamine (TEA) arediluted in 100 ml of EtOAc. At 0° C., 16.35 g of methanesulphonylchloride diluted in 35 ml of EtOAc are added dropwise to the reactionmedium with rapid stirring. 7.22 g of TEA are introduced, and thestirring is continued at ambient temperature for 4 h 30. 8.2 g ofmethanesulphonyl chloride are added dropwise at 15° C., and then thestirring is maintained at ambient temperature for 17 h. The precipitateis filtered off and washed with 3 times 50 ml of EtOAc. The organicphases are extracted with 100 ml of ice-cold water, 100 ml of water,with 3 times 50 ml of a saturated solution of NaHCO₃ and with twice 20ml of saturated NaCl, and are then dried over anhydrous Na₂SO₄. TheEtOAc is evaporated off, and 17.49 g of pale yellow translucent oil arerecovered. The analyses indicate that the product is in conformity.

Stage 2 Synthesis of1,1′-(disulphanediyldiethane-2,1-diyl)bis(4-methylpyridinium)dimethanesulphonate

3.51 g of picoline and 5 g of disulphanediyldiethane-2,1-diyl dimethanesulphonate are diluted in 5 ml of N-methylpyrrolidinone (NMP) and thenheated at 80° C. for 2 h with stirring. The stirring is maintained atambient temperature for 17 h. The reaction medium is made up with 50 mlof EtOAc, and then filtered, washed with 3 times 100 ml of EtOAc, anddried under vacuum in the presence of P₂O₅. 7.29 g of brown powder arerecovered. The analyses indicate that the product is in conformity andpure. ¹H NMR (400 MHz, DMSO-d₆) 2.31 (s, 6H), 2.62 (s, 6H), 3.40 (t,4H), 4.83 (t, 4H), 8.01 (d, 4H), 8.91 (d, 4H).

Stage 3 Synthesis of1,1′-(disulphanediyldiethane-2,1-diyl)bis[4-((E)-2-{4-[bis(2-hydroxyethyl)amino]phenyl}-vinyl)pyridinium]dimethanesulphonate [1]

4.32 g of 4-[bis(2-hydroxyethyl)amino]benzaldehyde, 10 ml of iPrOH and1.69 ml of pyrrolidine are mixed for 10 minutes with stirring. 1.18 mlof acetic acid are added and the mixture is stirred at ambienttemperature for 20 minutes. 5 g of1,1′-(disulphanediyldiethane-2,1-diyl)bis(4-methylpyridinium)dimethanesulphonate in suspension in 7 ml of iPrOH and 2 ml of methanol areadded. The reaction mixture is kept stirring for 24 h at ambienttemperature. The precipitate obtained is filtered off, washed with 100ml of acetone and then dried. 8.56 g of powder are recovered. Theanalyses indicate that the product is in conformity and pure. ¹H NMR(400 MHz, MeOH-d4) 2.71 (s, 6H), 3.35 (t, 4H), 3.64 (t, 8H), 3.76 (t,8H), 4.74 (t, 4H), 6.83 (d, 4H), 7.04 (d, 2H), 7.58 (d, 4H), 7.81 (d,2H), 7.96 (d, 4H), 8.56 (d, 4H).

Example 2 Synthesis of1,1′-(disulphanediyldiethane-2,1-diyl)bis[4-((E)-2-{4-[ethyl(2-hydroxyethyl)amino]-2-methylphenyl}-1-methylvinyl)pyridinium]dibromide[2]

Procedure

Stage 1 Synthesis of1,1′-(disulphanediyldiethane-2,1-diyl)bis(4-ethylpyridinium)dibromide

12.9 g of 4-ethylpyridine solubilized in 4 ml of NMP and 15 ml ofacetonitrile (ACN) are stirred and heated to 80° C. 15 g of1-bromo-2-(2-bromoethyldisulphanyl)-ethane diluted in 10 ml of ACN areadded dropwise to the medium for 30 minutes. The reaction mixture isstirred and refluxed for 4 h, and then heated at ambient temperature for17 h. 200 ml of acetone are added to the green solid obtained, the solidis broken up, and then filtered off, washed with 50 ml of acetone, andthen dried. 23.32 g of green powder are collected. The analyses indicatethat the product is in conformity.

Stage 2 Synthesis of1,1′-(disulphanediyldiethane-2,1-diyl)bis[4-((E)-2-{4-[ethyl(2-hydroxyethyl)amino]-2-methylphenyl}-1-methylvinyl)pyridinium]dibromide[2]

5 g of 4-[ethyl-(2-hydroxyethyl)amino]-2-methylbenzaldehyde, 10 ml ofiPrOH and 1.74 ml of pyrrolidine are mixed for 10 min with stirring.1.21 ml of acetic acid are added and the mixture is stirred at ambienttemperature for 20 min. 5 g of1,1′-(disulphanediyl-diethane-2,1-diyl)bis(4-ethylpyridinium)dibromidein suspension in 7 ml of iPrOH and 5 ml of methanol are added. Thereaction mixture is kept stirring for 1 week at ambient temperature. Thereaction mixture is conserved at ambient temperature for 4 weeks. Thereaction mixture is concentrated, the residue is extracted with anH₂O/CH₂Cl₂ mixture, the expected product is then extracted with butanol,the organic phase is concentrated, and the residue is taken up withethyl acetate. The precipitate obtained is filtered off and then dried.810 mg of powder are recovered. The analyses indicate that the productis in conformity.

Example 3 Synthesis of1,1′-(disulphanediyldiethane-2,1-diyl)bis[4-((E)-2-{4-[[3-(dimethylamino)propyl]-(methyl)amino]phenyl}vinyl)pyridinium]dimethanesulphonate [3]

Procedure

Stage 1 Synthesis of4-[[3-(dimethylamino)-propyl](methyl)amino]benzaldehyde

10 g of 4-fluorobenzaldehyde, 12 g of K₂CO₃ and 20 ml of NMP are stirredand heated at 50° C. 13 ml of N,N,N′-trimethyl-1,3-propanediamine areadded dropwise to the medium kept stirring and heated at 80° C. for 10h. After the reaction medium has been cooled to ambient temperature, 100ml of acetone are added. The precipitate obtained is filtered off, andthe filtrate is evaporated to dryness and then dried. 21.85 g of powderare recovered. The analyses indicate that the product is in conformity.

Stage 2 Synthesis of1,1′-(disulphanediyldiethane-2,1-diyl)bis[4-((E)-2-{4-[[3-(dimethylamino)-propyl](methyl)amino]phenyl}vinyl)pyridinium]dimethanesulphonate [3]

2 g of 4-[(3-dimethylaminopropyl)methylamino]benzaldehyde solubilized in5 ml of iPrOH, to which 585 μl of pyrrolidine are added, are stirred atambient temperature for 10 minutes. 408 μl of acetic acid are added tothe reaction medium, which is kept stirring at ambient temperature for20 minutes. 1.71 g of1,1′-(disulphanediyldiethane-2,1-diyl)bis(4-methyl-pyridinium)dimethanesulphonate presolubilized in 3 ml of iPrOH and 1 ml of methanol areintroduced into the medium and stirred at 20° C. for 4 days. 50 ml ofdiisopropyl ether are added to the reaction mixture cooled by means of abath of dry ice and acetone. The precipitate obtained is filtered offand then dried. 2.21 g of violet powder are recovered. The analysesindicate that the product is in conformity. ¹H NMR (400 MHz, MeOH-d4)1.84 (m, 4H), 2.34 (s, 12H), 2.48 (t, 4H), 2.71 (s, 6H), 3.06 (s, 6H),3.36 (t, 4H), 3.50 (t, 4H), 4.75 (t, 4H), 6.79 (d, 4H), 7.07 (d, 2H),7.60 (d, 4H), 7.84 (d, 2H), 7.98 (d, 4H), 8.57 (d, 4H).

Example 4 Synthesis of the1,1′-(disulphanediyl-diethane-2,1-diyl)bis{2-[(E)-2-(4-{methyl[3-(trimethylammonio)propyl]amino}phenyl)vinyl]pyridinium}salt[4]

Procedure

Stage 1 Synthesis of1,1′-(disulphanediyldiethane-2,1-diyl)bis(2-methylpyridinium)dibromide

A mixture of 56 g of 1-bromo-2-[(2-bromoethyl)-disulphanyl]ethane and 15ml of N-methylpyrrolidone (NMP) is poured dropwise onto 35 g of2-picoline with stirring, at 80° C. The mixture (white suspension) iskept stirring at 80° C. for 30 min, 100 ml of ACN are added, and thestirring is maintained at 80° C. for 90 min. After cooling, the solidobtained is filtered off, washed with 100 ml of ACN and then dried. 56.2g of brown powder are recovered. 45 g of this powder are suspended in300 ml of iPrOH, at reflux. Once the temperature has dropped to 40° C.,the solid is filtered off, washed with 3 times 100 ml of iPrOH and driedunder vacuum. 40.56 g of a light beige product are obtained. Theanalyses are in conformity with the expected structure.

Stage 2 Synthesis of3-[(4-formylphenyl)(methyl)-amino]-N,N,N-trimethylpropan-1-aminiummethane sulphonate

5 g of [[3-(dimethylamino)propyl](methyl)amino]benzaldehyde are dilutedin 15 ml of dichloromethane. 2.36 ml of dimethyl sulphate diluted in 10ml of dichloromethane are gradually added. The mixture is refluxed for 4h and then cooled to ambient temperature and poured into 100 ml of ethylacetate. The brown oil formed is separated by settling out, washed with100 ml of EtOAc, taken up in 200 ml of methanol and concentrated undervacuum. It is subsequently dissolved in a saturated solution of sodiumbicarbonate and of sodium chloride and extracted with butanol. Thebutanol phase is concentrated under vacuum and dried under vacuum in thepresence of P₂O₅, and the product is then used for the subsequent step.

Stage 3 Synthesis of the1,1′-(disulphanediyldiethane-2,1-diyl)bis{2-[(E)-2-(4-{methyl[3-(trimethylammonio)-propyl]amino}phenyl)vinyl]pyridinium}salt[4]

0.62 g of3-[(4-formylphenyl)(methyl)amino]-N,N,N-trimethylpropan-1-aminium methylsulphate solubilized in 2 ml of iPrOH and 3 ml of methanol, to which0.15 ml of pyrrolidine is added, is stirred at ambient temperature for10 minutes. 0.11 ml of acetic acid is added to the reaction medium,which is kept stirring at ambient temperature for 20 minutes. 0.41 g of1,1′-(disulphanediyldiethane-2,1-diyl)bis(2-methyl-pyridinium)dibromidepresolubilized in 2 ml of iPrOH and 2 ml of methanol are introduced intothe medium and stirred at 20° C. for 17 h. The analyses show thepresence of the expected product.

Example 5 Synthesis of4-((E)-2-{4-[bis(2-hydroxy-ethyl)amino]phenyl}vinyl)-1-(2-sulphanylethyl)-pyridiniummethane sulphonate [5]

Procedure

Synthesis of the4-((E)-2-{4-[bis(2-hydroxyethyl)-amino]phenyl}vinyl)-1-(2-sulphanylethyl)pyridiniumsalt [5]

88 mg of compound [1] are dissolved in 10 ml of water/ethanol mixture(1/1). 60 mg (2 eq.) of 3-[bis (2-carboxyethyl)phosphino]propanoic acidhydrochloride hydrate in solution in 1 ml of water and 21 mg (4 eq.) ofsodium bicarbonate in solution in 1 ml of water are added to themixture. After stirring at 40° C. for 30 minutes under an inertatmosphere, the analyses indicate that the mixture contains verypredominantly the expected product [5].

LC-MS analysis: LC-DAD (400-700 nm)

Column: Waters XTerra MS C18 5 μm (4.6×50) mm

Mobile phase: A: water+0.1% formic acid/B: acetonitrile

Linear gradient: T (min) A %/B %: 0 min 95/5; 8 min 0/100

Flow rate: 1 ml/min

Detection: UV diode array λ=400-700 nm

Retention time t=3.3 min

Relative purity>90%

MS (ESI+) m/z=345 corresponds to the mass peak for the monocation of theexpected product [5]

Dyeing Examples Example 1 Dyeing Process with Compounds [1] to [4]

Preparation of a Composition A

Disulphide dye from [1] to [4] 10⁻³ mol % Benzyl alcohol 4 gPolyethylene glycol 60 EO 6 g Hydroxyethylcellulose 0.7 gAlkylpolyglucoside in an aqueous 4.5 g solution containing 65% AMDemineralized water qs 100 gPreparation of a Composition B

Thioglycolic acid 1M Sodium hydroxide qs pH 8.5 Demineralized water qs100 g

At the time of use, compositions A (9 ml) and B (1 ml) are mixed, thenthe mixture obtained is applied to a lock of 1 g of dark hair (toneheight 4) for 30 minutes at ambient temperature (the locks are turnedover and reimpregnated after 15 minutes).

After rinsing with running water and drying, lightening of the hair thustreated is observed: the lock of tone height 4 has become visuallylighter than untreated control locks.

Example 2 Dyeing Process with Compound [5]

10 ml of fresh solution of compound [5] of the synthesis example areapplied to a lock of 1 g of hair of tone height 4 placed at the bottomof the same bowl for 30 minutes at ambient temperature (the locks areturned over and reimpregnated after 15 minutes).

The locks are subsequently rinsed with running water and dried.

After dyeing, the lock of tone height 4 has become visually lighter thanuntreated control locks.

Remanence with Respect to Successive Shampooing Operations:

The locks thus treated are divided into two, half are subjected to 5successive shampooing operations according to a cycle which compriseswetting the locks with water, washing with a conventional shampoo,rinsing with water, followed by drying.

Visual Observations

During the shampooing operations, there is no visible bleeding, theshampoo foam and the rinsing water are not coloured.

The colour observed on the locks is conserved and the lightening effectremains visible on the hair thus treated.

Results in the L*a*b* System:

The colour of the locks before and after the 5 washes was evaluated inthe L*a*b* system by means of a MINOLTA® CM 2600D spectrophotometer,(illuminant D65).

In this L*a*b* system, L* represents the luminosity, a* indicates thegreen/red colour axis and b* the blue/yellow colour axis. The higher thevalue of L, the lighter or weaker a colour, conversely, the lower thevalue of L, the darker or much stronger the colour. The higher the valueof a*, the redder the shade, and the higher the value of b*, the moreyellow the shade.

The variation in colouring between the TH4 (tone height 4) dyed andwashed locks of hair is measured by (ΔE) according to the followingequation:ΔE=√{square root over ((L*−L _(o)*)²+(a*−a _(o)*)²+(b*−b_(o)*)²)}{square root over ((L*−L _(o)*)²+(a*−a _(o)*)²+(b*−b_(o)*)²)}{square root over ((L*−L _(o)*)²+(a*−a _(o)*)²+(b*−b _(o)*)²)}

In this equation, L*, a* and b* represent the values measured afterdyeing, and L₀*, a₀* and b₀* represent the values measured before dyeing(or shampooing).

The greater the value of ΔE, the greater the difference in colourbetween TH4 locks and the coloured locks.

Treatment with the fluorescent dye on the TH4 locks ΔE After applicationof compound 1 according to the 8.38 invention After application ofcompound 1 according to the 8.66 invention and after 5 successiveshampooing operations After application of compound 2 according to the2.71 invention After application of compound 2 according to the 2.84invention and after 5 successive shampooing operations After applicationof compound 3 according to the 9.62 invention After application ofcompound 3 according to the 9.88 invention and after 5 successiveshampooing operations After application of compound 5 according to the5.27 invention After application of compound 5 according to the 5.25invention and after 5 successive shampooing operations

The results in the table above show that the coloring changes verylittle after 5 shampooing operations. Thus, the coloring and thelightening effect on the hair remains virtually unchanged, which shows avery good resistance to shampooing of the dyes of the invention.

Reflectance Results:

As shown in FIGS. 1, 2 and 3, the lightening effectiveness of thecompositions in accordance with the invention and the remittance of saidcompositions with respect to successive shampooing operations wereexpressed as a function of the reflectance of the hair. Thesereflectances are compared with the reflectance of a lock of untreatedhair of tone height TH4.

The reflectance is measured by means of a KONIKA-MINOLTA® CM 2600dspectrophotocolorimeter apparatus and after irradiation of the hair withvisible light in the wavelength range of from 400 to 700 nanometres.

It is first of all noted that the reflectance of a lock of hair treatedwith a composition according to the invention is greater than that ofthe untreated hair. The treated locks therefore appear to be lighter.

Furthermore, the results show that the reflectance of the locks of hairof tone height 4, treated with the compositions of the invention, changevery little after 5 shampooing operations. Thus, the colouring and thelightening effect on the hair remain virtually unchanged, which shows avery good resistance of the dyes of the invention to shampooingoperations.

1. At least one fluorescent entity chosen from those of formulae (I) and(II):

the organic and mineral acid salts, optical isomers and geometricalisomers, and the solvates thereof; wherein: R and R′″, which may beidentical or different, represent a hydroxyl group, an amino group(NR_(a)R_(b)) or an ammonium group (N⁺R_(a)R_(b)R_(c)), An⁻; with R_(a),R_(b) and R_(c), which may be identical or different, representing ahydrogen atom or a (C₁-C₄)alkyl group; or else two alkyl groups R_(a)and R_(b) of the amino or ammonium group form a heterocycle comprising 5to 7 members and optionally comprising another heteroatom which may beidentical to or different from that of the nitrogen atom and An⁻representing an anionic counterion; R′ and R″, which may be identical ordifferent, represent a hydrogen atom, a hydroxyl group, an amino group(NR_(a)R_(b)) or an ammonium group (N⁺R_(a)R_(b)R_(c)), An⁻; with R_(a),R_(b) and R_(c), which may be identical or different, representing ahydrogen atom or a (C₁-C₄)alkyl group; or else two alkyl groups R_(a)and R_(b) of the amino or ammonium group form a heterocycle comprising 5to 7 members and optionally comprising another heteroatom which may beidentical to or different from that of the nitrogen atom and An⁻representing an anionic counterion; R_(g), R′_(g), R″_(g), R′″_(g),R_(h), R′_(h), R″_(h) and R′″_(h), which may be identical or different,represent a hydrogen or halogen atom, an amino, (di)(C₁-C₄)alkylamino,cyano, carboxyl, hydroxyl, trifluoromethyl, acylamino, C₁-C₄ alkoxy,C₂-C₄ (poly)hydroxyalkoxy, (C₁-C₄)alkylcarbonyloxy,(C₁-C₄)alkoxycarbonyl, (C₁-C₄)alkylcarbonylamino, acylamino, carbamoylor (C₁-C₄)alkylsulphonylamino group, an aminosulphonyl radical, or a(C₁-C₁₆)alkyl radical optionally substituted with a group chosen from(C₁-C₁₂)alkoxy, hydroxyl, cyano, carboxyl, amino and(di)(C₁-C₄)alkylamino, or else the two alkyl radicals borne by thenitrogen atom of the amino group form a heterocycle comprising from 5 to7 members and optionally comprising another heteroatom which may beidentical to or different from that of the nitrogen atom; R′_(i),R″_(i), R′″_(i) and R″″_(i), which may be identical or different,represent a hydrogen atom or a (C₁-C₄)alkyl group; m and m′, which maybe identical or different, represent an integer ranging from 1 to 10; p,p′, q and q′, which may be identical or different, represent an integerranging from 1 to 6; M′ represents an anionic counterion; and Yrepresents: i) a hydrogen atom; ii) an alkali metal; iii) an alkalineearth metal; iv) an ammonium group: N⁺R^(α)R^(β)R^(γ)R^(δ) or aphosphonium group: P⁺R^(α)R^(β)R^(γ)R^(δ) with R^(α), R^(β), R^(γ), andR^(δ), which may be identical or different, representing a hydrogen atomor a (C₁-C₄)alkyl group; or v) a thiol-function-protecting group; itbeing understood that: when the at least one fluorescent entity chosenfrom those of formulae (I) and (II) contains other cationic parts, it isassociated with at least one anionic counterion allowing formula (I) or(II) to achieve electroneutrality.
 2. The at least one fluorescententity according to claim 1, wherein Y represents a hydrogen atom or analkali metal.
 3. The at least one fluorescent entity of formula (II)according to claim 1, wherein Y represents a protecting group.
 4. The atleast one fluorescent entity of formula (II) according to claim 3,wherein Y represents a protecting group chosen from the followingradicals: (C₁-C₄)alkylcarbonyl; (C₁-C₄)alkylthiocarbonyl;(C₁-C₄)alkoxycarbonyl; (C₁-C₄)alkoxythiocarbonyl;(C₁-C₄)alkylthiothiocarbonyl; (di)(C₁-C₄)(alkyl)aminocarbonyl;(di)(C₁-C₄)(alkyl)aminothiocarbonyl; arylcarbonyl such asphenylcarbonyl; aryloxycarbonyl; aryl(C₁-C₄)alkoxycarbonyl;(di)(C₁-C₄)(alkyl)aminocarbonyl; (C₁-C₄)(alkyl)arylaminocarbonyl;carboxyl; SO₃ ⁻ M⁺ with M⁺ representing an alkali metal or alternativelySO₃ ⁻ M′ with M′ representing an anionic counterion; optionallysubstituted aryl; optionally substituted heteroaryl; optionallycationic, optionally substituted heterocycloalkyl; isothiouronium—C(NR′^(c)R′^(d))═N⁺R′^(e)R′^(f) An⁻ with R′^(c), R′^(d), R′^(e) andR′^(f), which may be identical or different, representing a hydrogenatom or a (C₁-C₄)alkyl group; and An⁻ represents a counterion;isothiourea —C(NR′^(c)R′^(d))═NR′^(e); wherein R′^(c), R′^(d), andR′^(e), which may be identical or different, represent a hydrogen atomor a (C₁-C₄)alkyl group; optionally substituted (di)aryl(C₁-C₄)alkyl;optionally substituted (di)heteroaryl(C₁-C₄)alkyl; CR¹R²R³ with R¹, R²and R³, which may be identical or different, representing a halogen atomor a group chosen from: (C₁-C₄)alkyl; (C₁-C₄)alkoxy; optionallysubstituted aryl; optionally substituted heteroaryl; and P (Z¹)R′¹R′²R′³with and R′², which may be identical or different, representing ahydroxyl, (C₁-C₄)alkoxy or alkyl group, R′³ representing a hydroxyl or(C₁-C₄)alkoxy group and Z¹ representing an oxygen or sulphur atom; asterically hindered cyclic group; and optionally substitutedalkoxy(C₁-C₄)alkyl.
 5. The at least one fluorescent entity according toclaim 1, wherein Y represents an alkali metal or a protecting groupchosen from: (C₁-C₄)alkylcarbonyl; arylcarbonyl; (C₁-C₄)alkoxycarbonyl;aryloxycarbonyl; aryl(C₁-C₄)alkoxycarbonyl;(di)(C₁-C₄)(alkyl)aminocarbonyl; (C₁-C₄)(alkyl)arylaminocarbonyl;optionally substituted aryl; 5- or 6-membered cationic monocyclicheteroaryl; 8- to 11-membered cationic bicyclic heteroaryl; cationicheterocycle of formula below:

wherein An⁻ represents a counterion isothiouronium —C(NH₂)═N⁺H₂An⁻,wherein An- represents a counterion; isothiourea —C(NH₂)═NH; SO₃ ⁻ M⁺with M⁺ representing an alkali metal or alternatively SO₃ ⁻ M′ with M′representing an anionic counterion.
 6. The at least one fluorescententity according to claim 1, chosen from those of formula (Ia) and(IIa):

wherein: R and R′″, which may be identical or different, represent ahydroxyl group, an amino group (NR_(a)R_(b)) or an ammonium group(N⁺R_(a)R_(b)R_(c)), An⁻; with R_(a), R_(b) and R_(c), which may beidentical or different, representing a hydrogen atom or a (C₁-C₄)alkylgroup; or else two alkyl groups R_(a) and R_(b) of the amino or ammoniumgroup form a heterocycle comprising 5 to 7 members and optionallycomprising another heteroatom which may be identical to or differentfrom that of the nitrogen atom and An⁻ representing an anioniccounterion; R′ and R″, which may be identical or different, represent ahydrogen atom, a hydroxyl group, an amino group (NR_(a)R_(b)) or anammonium group (N⁺R_(a)R_(b)R_(c)), An⁻; with R_(a), R_(b) and R_(c),which may be identical or different, representing a hydrogen atom or a(C₁-C₄)alkyl group; or else two alkyl groups R_(a) and R_(b) of theamino or ammonium group form a heterocycle comprising 5 to 7 members andoptionally comprising another heteroatom which may be identical to ordifferent from that of the nitrogen atom and An⁻ representing an anioniccounterion; R_(g), R′_(g), R″_(g), R′″_(g), R_(h), R′_(h), R″_(h), andR′″_(h), which may be identical or different, represent a hydrogen orhalogen atom, an amino, (di)(C₁-C₄)alkylamino, cyano, carboxyl,hydroxyl, trifluoromethyl, acylamino, C₁-C₄ alkoxy, C₂-C₄(poly)hydroxyalkoxy, (C₁-C₄)alkylcarbonyloxy, (C₁-C₄)alkoxycarbonyl,(C₁-C₄)alkylcarbonylamino, acylamino, carbamoyl or(C₁-C₄)alkylsulphonylamino group, an aminosulphonyl radical, or a(C₁-C₁₆)alkyl radical optionally substituted with a group chosen from(C₁-C₁₂)alkoxy, hydroxyl, cyano, carboxyl, amino and(di)(C₁-C₄)alkylamino, or else the two alkyl radicals borne by thenitrogen atom of the amino group form a heterocycle comprising from 5 to7 members and optionally comprising another heteroatom which may beidentical to or different from that of the nitrogen atom; R′_(i),R″_(i), R′″_(i) and R″″_(i), which may be identical or different,represent a hydrogen atom or a (C₁-C₄)alkyl group; m and m′, which maybe identical or different, represent an integer ranging from 1 to 10; p,p′, q and q′, which may be identical or different, represent an integerranging from 1 to 6; M′ represents an anionic counterion; and Yrepresents: i) a hydrogen atom; ii) an alkali metal; iii) an alkalineearth metal; iv) an ammonium group: N⁺R^(α)R^(β)R^(γ)R^(δ) or aphosphonium group: P⁺R^(α)R^(β)R^(γ)R^(δ) with R^(α), R^(β), R^(γ) andR^(δ), which may be identical or different, representing a hydrogen atomor a (C₁-C₄)alkyl group; or v) a thiol-function-protecting group; itbeing understood that: when the at least one entity chosen from those offormulae (I) and (II) contains other cationic parts, it is associatedwith at least one anionic counterion allowing formula (I) or (II) toachieve electroneutrality.
 7. The at least one fluorescent entityaccording to claim 1, wherein the at least one fluorescent entity ischosen from those of formulae 1-32:

with M′ representing an anionic counterion.
 8. A dye compositioncomprising, in a suitable cosmetic medium, at least one fluorescententity chosen from those of formulae (I) and (II):

the organic and mineral acid salts, optical isomers and geometricalisomers, and the solvates thereof; wherein: R and R′″, which may beidentical or different, represent a hydroxyl group, an amino group(NR_(a)R_(b)) or an ammonium group (N⁺R_(a)R_(b)R_(c)), An⁻; with R_(a),R_(b) and R_(c), which may be identical or different, representing ahydrogen atom or a (C₁-C₄)alkyl group; or else two alkyl groups R_(a)and R_(b) of the amino or ammonium group form a heterocycle comprising 5to 7 members and optionally comprising another heteroatom which may beidentical to or different from that of the nitrogen atom and An⁻representing an anionic counterion; R′ and R″, which may be identical ordifferent, represent a hydrogen atom, a hydroxyl group, an amino group(NR_(a)R_(b)) or an ammonium group (N⁺R_(a)R_(b)R_(c)), An⁻; with R_(a),R_(b) and R_(c), which may be identical or different, representing ahydrogen atom or a (C₁-C₄)alkyl group; or else two alkyl groups R_(a)and R_(b) of the amino or ammonium group form a heterocycle comprising 5to 7 members and optionally comprising another heteroatom which may beidentical to or different from that of the nitrogen atom and An⁻representing an anionic counterion; R_(g), R′_(g), R″_(g), R′″_(g),R_(h), R′_(h), R″_(h), and R′″_(h), which may be identical or different,represent a hydrogen or halogen atom, an amino, (di)(C₁-C₄)alkylamino,cyano, carboxyl, hydroxyl, trifluoromethyl, acylamino, C₁-C₄ alkoxy,C₂-C₄ (poly)hydroxyalkoxy, (C₁-C₄)alkylcarbonyloxy,(C₁-C₄)alkoxycarbonyl, (C₁-C₄)alkylcarbonylamino, acylamino, carbamoylor (C₁-C₄)alkylsulphonylamino group, an aminosulphonyl radical, or a(C₁-C₁₆)alkyl radical optionally substituted with a group chosen from(C₁-C₁₂)alkoxy, hydroxyl, cyano, carboxyl, amino and(di)(C₁-C₄)alkylamino, or else the two alkyl radicals borne by thenitrogen atom of the amino group form a heterocycle comprising from 5 to7 members and optionally comprising another heteroatom which may beidentical to or different from that of the nitrogen atom; R′_(i),R″_(i), R′″_(i) and R″″_(i), which may be identical or different,represent a hydrogen atom or a (C₁-C₄)alkyl group; m and m′, which maybe identical or different, represent an integer ranging from 1 to 10; p,p′, q and q′, which may be identical or different, represent an integerranging from 1 to 6; M′ represents an anionic counterion; and Yrepresents: i) a hydrogen atom; ii) an alkali metal; iii) an alkalineearth metal; iv) an ammonium group: N⁺R^(α)R^(β)R^(γ)R^(δ) or aphosphonium group: P⁺R^(α)R^(β)R^(γ)R^(δ) with R^(α), R^(β), R^(γ) andR^(δ), which may be identical or different, representing a hydrogen atomor a (C₁-C₄)alkyl group; or v) a thiol-function-protecting group; itbeing understood that: when the at least one entity chosen from those offormulae (I) and (II) contains other cationic parts, it is associatedwith at least one anionic counterion allowing formula (I) or (II) toachieve electroneutrality.
 9. The dye composition according to claim 8,further comprising at least one reducing agent.
 10. The dye compositionaccording to claim 9, wherein the at least one reducing agent is chosenfrom cysteine and salts thereof homocysteine and salts thereof,thiolactic acid and salts thereof, phosphines, bisulphite, sulphites,thioglycolic acid and esters thereof, borohydrides and derivativesthereof, sodium salts, lithium salts, potassium salts, calcium salts,quaternary ammonium salts; and catechol borane.
 11. The dye compositionaccording to claim 8, wherein the at least one fluorescent entity ispresent in an amount ranging from 0.001% to 50% by weight, relative tothe total weight of the composition.
 12. A process for dyeing keratinmaterials, comprising: applying to the keratin materials at least onedye composition comprising at least one fluorescent entity chosen fromformulae (I) and (II)

the organic and mineral acid salts, optical isomers and geometricalisomers, and the solvates thereof; wherein: R and R′″, which may beidentical or different, represent a hydroxyl group, an amino group(NR_(a)R_(b)) or an ammonium group (N⁺R_(a)R_(b)R_(c)), An⁻; with R_(a),R_(b) and R_(c), which may be identical or different, representing ahydrogen atom or a (C₁-C₄)alkyl group; or else two alkyl groups R_(a)and R_(b) of the amino or ammonium group form a heterocycle comprising 5to 7 members and optionally comprising another heteroatom which may beidentical to or different from that of the nitrogen atom and An⁻representing an anionic counterion; R′ and R″, which may be identical ordifferent, represent a hydrogen atom, a hydroxyl group, an amino group(NR_(a)R_(b)) or an ammonium group (N⁺R_(a)R_(b)R_(c)), An⁻; with R_(a),R_(b) and R_(c), which may be identical or different, representing ahydrogen atom or a (C₁-C₄)alkyl group; or else two alkyl groups R_(a)and R_(b) of the amino or ammonium group form a heterocycle comprising 5to 7 members and optionally comprising another heteroatom which may beidentical to or different from that of the nitrogen atom and An⁻representing an anionic counterion; R_(g), R′_(g), R″_(g), R′″_(g),R_(h), R′_(h), R″_(h) and R′″_(h), which may be identical or different,represent a hydrogen or halogen atom, an amino, (di)(C₁-C₄)alkylamino,cyano, carboxyl, hydroxyl, trifluoromethyl, acylamino, C₁-C₄ alkoxy,C₂-C₄ (poly)hydroxyalkoxy, (C₁-C₄)alkylcarbonyloxy,(C₁-C₄)alkoxycarbonyl, (C₁-C₄)alkylcarbonylamino, acylamino, carbamoylor (C₁-C₄)alkylsulphonylamino group, an aminosulphonyl radical, or a(C₁-C₁₆)alkyl radical optionally substituted with a group chosen from(C₁-C₁₂)alkoxy, hydroxyl, cyano, carboxyl, amino and(di)(C₁-C₄)alkylamino, or else the two alkyl radicals borne by thenitrogen atom of the amino group form a heterocycle comprising from 5 to7 members and optionally comprising another heteroatom which may beidentical to or different from that of the nitrogen atom; R′_(i),R″_(i), R′″_(i) and R″″_(i), which may be identical or different,represent a hydrogen atom or a (C₁-C₄)alkyl group; m and m′, which maybe identical or different, represent an integer ranging from 1 to 10; p,p′, q and q′, which may be identical or different, represent an integerranging from 1 to 6; M′ represents an anionic counterion; and Yrepresents: i) a hydrogen atom; ii) an alkali metal; iii) an alkalineearth metal; iv) an ammonium group: N⁺R^(α)R^(β)R^(γ)R^(δ) or aphosphonium group: P⁺R^(α)R^(β)R^(γ)R^(δ) with R^(α), R^(β), R^(γ) andR^(δ), which may be identical or different, representing a hydrogen atomor a (C₁-C₄)alkyl group; or v) a thiol-function-protecting group; itbeing understood that: when the at least one entity chosen from those offormulae (I) and (II) contains other cationic parts, it is associatedwith at least one anionic counterion allowing formula (I) or (II) toachieve electroneutrality; and optionally applying at least one reducingagent.
 13. The process for dyeing keratin materials according to claim12, wherein, when the at least one fluorescent entity of formula (II)comprises a thiol-function protecting group Y, the application ispreceded by a deprotection step.
 14. The process for dyeing keratinmaterials according to claim 12, wherein the keratin materials are darkkeratin fibers having a tone height of less than or equal to
 6. 15. Theprocess for dyeing keratin materials according to claim 12, comprisingapplying at least one reducing agent before or after applying thecomposition comprising the at least one fluorescent entity.
 16. Theprocess for dyeing keratin materials according to claim 12, wherein thecomposition further comprises at least one oxidizing agent.
 17. Theprocess for dyeing keratin materials according to claim 12, furthercomprising applying at least one oxidizing agent to the keratinmaterials.
 18. A multicompartment device comprising at least one firstcompartment-comprising a dye composition comprising at least onefluorescent entity chosen from those of formulae (I) and (II)

the organic and mineral acid salts, optical isomers and geometricalisomers, and the solvates thereof; wherein: R and R′″, which may beidentical or different, represent a hydroxyl group, an amino group(NR_(a)R_(b)) or an ammonium group (N⁺R_(a)R_(b)R_(c)), An⁻; with R_(a),R_(b) and R_(c), which may be identical or different, representing ahydrogen atom or a (C₁-C₄)alkyl group; or else two alkyl groups R_(a)and R_(b) of the amino or ammonium group form a heterocycle comprising 5to 7 members and optionally comprising another heteroatom which may beidentical to or different from that of the nitrogen atom and An⁻representing an anionic counterion; R′ and R″, which may be identical ordifferent, represent a hydrogen atom, a hydroxyl group, an amino group(NR_(a)R_(b)) or an ammonium group (N⁺R_(a)R_(b)R_(c)), An⁻; with R_(a),R_(b) and R_(c), which may be identical or different, representing ahydrogen atom or a (C₁-C₄)alkyl group; or else two alkyl groups R_(a)and R_(b) of the amino or ammonium group form a heterocycle comprising 5to 7 members and optionally comprising another heteroatom which may beidentical to or different from that of the nitrogen atom and An⁻representing an anionic counterion; R_(g), R′_(g), R″_(g), R′″_(g),R_(h), R′_(h), R″_(h) and R′″_(h), which may be identical or different,represent a hydrogen or halogen atom, an amino, (di)(C₁-C₄)alkylamino,cyano, carboxyl, hydroxyl, trifluoromethyl, acylamino, C₁-C₄ alkoxy,C₂-C₄ (poly)hydroxyalkoxy, (C₁-C₄)alkylcarbonyloxy,(C₁-C₄)alkoxycarbonyl, (C₁-C₄)alkylcarbonylamino, acylamino, carbamoylor (C₁-C₄)alkylsulphonylamino group, an aminosulphonyl radical, or a(C₁-C₁₆)alkyl radical optionally substituted with a group chosen from(C₁-C₁₂)alkoxy, hydroxyl, cyano, carboxyl, amino and(di)(C₁-C₄)alkylamino, or else the two alkyl radicals borne by thenitrogen atom of the amino group form a heterocycle comprising from 5 to7 members and optionally comprising another heteroatom which may beidentical to or different from that of the nitrogen atom; R′_(i),R″_(i), R′″_(i) and R″″_(i), which may be identical or different,represent a hydrogen atom or a (C₁-C₄)alkyl group; m and m′, which maybe identical or different, represent an integer ranging from 1 to 10; p,p′, q and q′, which may be identical or different, represent an integerranging from 1 to 6; M′ represents an anionic counterion; and Yrepresents: i) a hydrogen atom; ii) an alkali metal; iii) an alkalineearth metal; iv) an ammonium group: N⁺R^(α)R^(β)R^(γ)R^(δ) or aphosphonium group: P⁺R^(α)R^(β)R^(γ)R^(δ) with R^(β), R^(β), R^(γ) andR^(δ), which may be identical or different, representing a hydrogen atomor a (C₁-C₄)alkyl group; or v) a thiol-function-protecting group; itbeing understood that: when the at least one entity chosen from those offormulae (I) and (II) contains other cationic parts, it is associatedwith at least one anionic counterion allowing formula (I) or (II) toachieve electroneutrality; and at least one second compartmentcomprising at least one reducing agent.
 19. The multicompartment deviceaccording to claim 18, comprising at least one third compartmentcomprising at least one oxidizing agent.
 20. A process for lighteningdark keratin fibers comprising, applying to dark keratin fibers at leastone fluorescent entity chosen from those of formulae (I) and (II)

the organic and mineral acid salts, optical isomers and geometricalisomers, and the solvates thereof; wherein: R and R′″, which may beidentical or different, represent a hydroxyl group, an amino group(NR_(a)R_(b)) or an ammonium group (N⁺R_(a)R_(b)R_(c)), An⁻, with R_(a),R_(b) and R_(c), which may be identical or different, representing ahydrogen atom or a (C₁-C₄)alkyl group; or else two alkyl groups R_(a)and R_(b) of the amino or ammonium group form a heterocycle comprising 5to 7 members and optionally comprising another heteroatom which may beidentical to or different from that of the nitrogen atom and An⁻representing an anionic counterion; R′ and R″, which may be identical ordifferent, represent a hydrogen atom, a hydroxyl group, an amino group(NR_(a)R_(b)) or an ammonium group (N⁺R_(a)R_(b)R_(c)), An⁻; with R_(a),R_(b) and R_(c), which may be identical or different, representing ahydrogen atom or a (C₁-C₄)alkyl group; or else two alkyl groups R_(a)and R_(b) of the amino or ammonium group form a heterocycle comprising 5to 7 members and optionally comprising another heteroatom which may beidentical to or different from that of the nitrogen atom and An⁻representing an anionic counterion; R_(g), R′_(g), R″_(g), R′″_(g),R_(h), R′_(h), R″_(h) and R′″_(h), which may be identical or different,represent a hydrogen or halogen atom, an amino, (di)(C₁-C₄)alkylamino,cyano, carboxyl, hydroxyl, trifluoromethyl, acylamino, C₁-C₄ alkoxy,C₂-C₄ (poly)hydroxyalkoxy, (C₁-C₄)alkylcarbonyloxy,(C₁-C₄)alkoxycarbonyl, (C₁-C₄)alkylcarbonylamino, acylamino, carbamoylor (C₁-C₄)alkylsulphonylamino group, an aminosulphonyl radical, or a(C₁-C₁₆)alkyl radical optionally substituted with a group chosen from(C₁-C₁₂)alkoxy, hydroxyl, cyano, carboxyl, amino and(di)(C₁-C₄)alkylamino, or else the two alkyl radicals borne by thenitrogen atom of the amino group form a heterocycle comprising from 5 to7 members and optionally comprising another heteroatom which may beidentical to or different from that of the nitrogen atom; R′_(i),R″_(i), R′″_(i), and R″″_(i), which may be identical or different,represent a hydrogen atom or a (C₁-C₄)alkyl group; m and m′, which maybe identical or different, represent an integer ranging from 1 to 10; p,p′, q and q′, which may be identical or different, represent an integerranging from 1 to 6; M′ represents an anionic counterion; and Yrepresents: i) a hydrogen atom; ii) an alkali metal; iii) an alkalineearth metal; iv) an ammonium group: N⁺R^(α)R^(β)R^(γ)R^(δ) or aphosphonium group: P⁺R^(α)R^(β)R^(γ)R^(δ) with R^(α), R^(β), R^(γ) andR^(δ), which may be identical or different, representing a hydrogen atomor a (C₁-C₄)alkyl group; or v) a thiol-function-protecting group; itbeing understood that: when the at least one entity chosen from those offormulae (I) and (II) contains other cationic parts, it is associatedwith at least one anionic counterion allowing formula (I) or (II) toachieve electroneutrality, and optionally applying at least one reducingagent.